ER Reorganization is Remarkably Induced in COS-7 Cells Accumulating Transmembrane Protein Receptors Not Competent for Export from the Endoplasmic Reticulum

2014 ◽  
Vol 247 (11) ◽  
pp. 1149-1159 ◽  
Author(s):  
Massimo D’Agostino ◽  
Arianna Crespi ◽  
Elena Polishchuk ◽  
Serena Generoso ◽  
Gianluca Martire ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Transmembrane Protein ◽  
Protein Receptors

scholarly journals Structure-Function Analysis of the Endoplasmic Reticulum Oxidoreductase TMX3 Reveals Interdomain Stabilization of the N-terminal Redox-active Domain

2007 ◽  
Vol 282 (46) ◽  
pp. 33859-33867 ◽  
Author(s):  
Johannes Haugstetter ◽  
Michael Andreas Maurer ◽  
Thomas Blicher ◽  
Martin Pagac ◽  
Gerhard Wider ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Disulfide Isomerase ◽  
Function Analysis ◽  
Transmembrane Protein ◽  
Reduced Form ◽  
Disulfide Isomerase ◽  
Binding Domains ◽  
Redox Active ◽  
Protein Disulfide ◽  
Protein Disulfide Isomerase Family

Disulfide bond formation in the endoplasmic reticulum is catalyzed by enzymes of the protein disulfide-isomerase family that harbor one or more thioredoxin-like domains. We recently discovered the transmembrane protein TMX3, a thiol-disulfide oxidoreductase of the protein disulfide-isomerase family. Here, we show that the endoplasmic reticulum-luminal region of TMX3 contains three thioredoxin-like domains, an N-terminal redox-active domain (named a) followed by two enzymatically inactive domains (b and b′). Using the recombinantly expressed TMX3 domain constructs a, ab, and abb′, we compared structural stability and enzymatic properties. By structural and biophysical methods, we demonstrate that the reduced a domain has features typical of a globular folded domain that is, however, greatly destabilized upon oxidization. Importantly, interdomain stabilization by the b domain renders the a domain more resistant toward chemical denaturation and proteolysis in both the oxidized and reduced form. In combination with molecular modeling studies of TMX3 abb′, the experimental results provide a new understanding of the relationship between the multidomain structure of TMX3 and its function as a redox enzyme. Overall, the data indicate that in addition to their role as substrate and co-factor binding domains, redox-inactive thioredoxin-like domains also function in stabilizing neighboring redox-active domains.

scholarly journals An essential dimer-forming subregion of the endoplasmic reticulum stress sensor Ire1

2005 ◽  
Vol 391 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Daisuke Oikawa ◽  
Yukio Kimata ◽  
Masato Takeuchi ◽  
Kenji Kohno
Keyword(s):  
Endoplasmic Reticulum ◽  
Recombinant Protein ◽  
Endoplasmic Reticulum Stress ◽  
Transmembrane Protein ◽  
Type I ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
Recombinant Fragments ◽  
Made In

The luminal domain of the type I transmembrane protein Ire1 senses endoplasmic reticulum stress by an undefined mechanism to up-regulate the signalling pathway for the unfolded protein response. Previously, we proposed that the luminal domain of yeast Ire1 is divided into five subregions, termed subregions I–V sequentially from the N-terminus. Ire1 lost activity when internal deletions of subregion II or IV were made. In the present paper, we show that partial proteolysis of a recombinant protein consisting of the Ire1 luminal domain suggests that subregions II–IV are tightly folded. We also show that a recombinant protein of subregions II–IV formed homodimers, and that this homodimer formation was impaired by an internal deletion of subregion IV. Furthermore, recombinant fragments of subregion IV exhibited a self-binding ability. Therefore, although its sequence is little conserved evolutionarily, subregion IV plays an essential role to promote Ire1 dimer formation.

A novel transmembrane protein defines the endoplasmic reticulum stress-induced cell death pathway

2017 ◽  
Vol 486 (1) ◽  
pp. 149-155 ◽  
Author(s):  
Tomoya Tamaki ◽  
Kenta Kamatsuka ◽  
Taku Sato ◽  
Shuntaro Morooka ◽  
Kosuke Otsuka ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Endoplasmic Reticulum Stress ◽  
Transmembrane Protein ◽  
Cell Death Pathway

scholarly journals Enigmatic origin of the poxvirus membrane from the endoplasmic reticulum shown by 3D imaging of vaccinia virus assembly mutants

2017 ◽  
Vol 114 (51) ◽  
pp. E11001-E11009 ◽  
Author(s):  
Andrea S. Weisberg ◽  
Liliana Maruri-Avidal ◽  
Himani Bisht ◽  
Bryan T. Hansen ◽  
Cindi L. Schwartz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Vaccinia Virus ◽  
Virus Assembly ◽  
Transmembrane Protein ◽  
Membrane Dynamics ◽  
Deletion Mutants ◽  
Viral Membrane ◽  
Transmission Electron

The long-standing inability to visualize connections between poxvirus membranes and cellular organelles has led to uncertainty regarding the origin of the viral membrane. Indeed, there has been speculation that viral membranes form de novo in cytoplasmic factories. Another possibility, that the connections are too short-lived to be captured by microscopy during a normal infection, motivated us to identify and characterize virus mutants that are arrested in assembly. Five conserved vaccinia virus proteins, referred to as Viral Membrane Assembly Proteins (VMAPs), that are necessary for formation of immature virions were found. Transmission electron microscopy studies of two VMAP deletion mutants had suggested retention of connections between viral membranes and the endoplasmic reticulum (ER). We now analyzed cells infected with each of the five VMAP deletion mutants by electron tomography, which is necessary to validate membrane continuity, in addition to conventional transmission electron microscopy. In all cases, connections between the ER and viral membranes were demonstrated by 3D reconstructions, supporting a role for the VMAPs in creating and/or stabilizing membrane scissions. Furthermore, coexpression of the viral reticulon-like transmembrane protein A17 and the capsid-like scaffold protein D13 was sufficient to form similar ER-associated viral structures in the absence of other major virion proteins. Determination of the mechanism of ER disruption during a normal VACV infection and the likely participation of both viral and cell proteins in this process may provide important insights into membrane dynamics.

3D3/lyric: a novel transmembrane protein of the endoplasmic reticulum and nuclear envelope, which is also present in the nucleolus

2004 ◽  
Vol 294 (1) ◽  
pp. 94-105 ◽  
Author(s):  
Heidi G.E Sutherland ◽  
Yun Wah Lam ◽  
Stephanie Briers ◽  
Angus I Lamond ◽  
Wendy A Bickmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Transmembrane Protein

scholarly journals Autophagosome formation in relation to the endoplasmic reticulum

2020 ◽  
Vol 27 (1) ◽  
Author(s):  
Yo-hei Yamamoto ◽  
Takeshi Noda
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
De Novo ◽  
Transmembrane Protein ◽  
Lipid Transfer ◽  
Membrane Structures ◽  
Autophagosome Formation ◽  
Selective Autophagy ◽  
The Relationship ◽  
Er Membrane

Abstract Autophagy is a process in which a myriad membrane structures called autophagosomes are formed de novo in a single cell, which deliver the engulfed substrates into lysosomes for degradation. The size of the autophagosomes is relatively uniform in non-selective autophagy and variable in selective autophagy. It has been recently established that autophagosome formation occurs near the endoplasmic reticulum (ER). In this review, we have discussed recent advances in the relationship between autophagosome formation and endoplasmic reticulum. Autophagosome formation occurs near the ER subdomain enriched with phospholipid synthesizing enzymes like phosphatidylinositol synthase (PIS)/CDP-diacylglycerol-inositol 3-phosphatidyltransferase (CDIPT) and choline/ethanolamine phosphotransferase 1 (CEPT1). Autophagy-related protein 2 (Atg2), which is involved in autophagosome formation has a lipid transfer capacity and is proposed to directly transfer the lipid molecules from the ER to form autophagosomes. Vacuole membrane protein 1 (VMP1) and transmembrane protein 41b (TMEM41b) are ER membrane proteins that are associated with the formation of the subdomain. Recently, we have reported that an uncharacterized ER membrane protein possessing the DNAJ domain, called ERdj8/DNAJC16, is associated with the regulation of the size of autophagosomes. The localization of ERdj8/DNAJC16 partially overlaps with the PIS-enriched ER subdomain, thereby implying its association with autophagosome size determination.

scholarly journals The synaptic vesicle SNARE neuronal Synaptobrevin promotes endolysosomal degradation and prevents neurodegeneration

2012 ◽  
Vol 196 (2) ◽  
pp. 261-276 ◽  
Author(s):  
Adam Haberman ◽  
W. Ryan Williamson ◽  
Daniel Epstein ◽  
Dong Wang ◽  
Srisha Rina ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Transmembrane Protein ◽  
Primary Defect ◽  
Endosomal Sorting ◽  
Synaptic Vesicle Exocytosis ◽  
Cathepsin Proteases ◽  
Core Proteins ◽  
Protein Receptors ◽  
Vesicle Exocytosis ◽  
Photoreceptor Neurons

Soluble NSF attachment protein receptors (SNAREs) are the core proteins in membrane fusion. The neuron-specific synaptic v-SNARE n-syb (neuronal Synaptobrevin) plays a key role during synaptic vesicle exocytosis. In this paper, we report that loss of n-syb caused slow neurodegeneration independent of its role in neurotransmitter release in adult Drosophila melanogaster photoreceptor neurons. In addition to synaptic vesicles, n-Syb localized to endosomal vesicles. Loss of n-syb lead to endosomal accumulations, transmembrane protein degradation defects, and a secondary increase in autophagy. Our evidence suggests a primary defect of impaired delivery of vesicles that contain degradation proteins, including the acidification-activated Cathepsin proteases and the neuron-specific proton pump and V0 adenosine triphosphatase component V100. Overexpressing V100 partially rescued n-syb–dependent degeneration through an acidification-independent endosomal sorting mechanism. Collectively, these findings reveal a role for n-Syb in a neuron-specific sort-and-degrade mechanism that protects neurons from degeneration. Our findings further shed light on which intraneuronal compartments exhibit increased or decreased neurotoxicity.

scholarly journals Cytosolic Phosphorylation of Calnexin Controls Intracellular Ca2+ Oscillations via an Interaction with Serca2b

2000 ◽  
Vol 149 (6) ◽  
pp. 1235-1248 ◽  
Author(s):  
H. Llewelyn Roderick ◽  
James D. Lechleiter ◽  
Patricia Camacho
Keyword(s):  
Endoplasmic Reticulum ◽  
Xenopus Oocytes ◽  
Transmembrane Protein ◽  
Calcium Atpase ◽  
Site Directed Mutagenesis ◽  
Serine Residue ◽  
Endoplasmic Reticulum Calcium ◽  
Inositol 1,4,5 Trisphosphate ◽  
Functional Inhibition ◽  
Cytosolic Domain

Calreticulin (CRT) and calnexin (CLNX) are lectin chaperones that participate in protein folding in the endoplasmic reticulum (ER). CRT is a soluble ER lumenal protein, whereas CLNX is a transmembrane protein with a cytosolic domain that contains two consensus motifs for protein kinase (PK) C/proline- directed kinase (PDK) phosphorylation. Using confocal Ca2+ imaging in Xenopus oocytes, we report here that coexpression of CLNX with sarco endoplasmic reticulum calcium ATPase (SERCA) 2b results in inhibition of intracellular Ca2+ oscillations, suggesting a functional inhibition of the pump. By site-directed mutagenesis, we demonstrate that this interaction is regulated by a COOH-terminal serine residue (S562) in CLNX. Furthermore, inositol 1,4,5-trisphosphate– mediated Ca2+ release results in a dephosphorylation of this residue. We also demonstrate by coimmunoprecipitation that CLNX physically interacts with the COOH terminus of SERCA2b and that after dephosphorylation treatment, this interaction is significantly reduced. Together, our results suggest that CRT is uniquely regulated by ER lumenal conditions, whereas CLNX is, in addition, regulated by the phosphorylation status of its cytosolic domain. The S562 residue in CLNX acts as a molecular switch that regulates the interaction of the chaperone with SERCA2b, thereby affecting Ca2+ signaling and controlling Ca2+-sensitive chaperone functions in the ER.

scholarly journals Endoplasmic reticulum transmembrane protein TMTC3 contributes to O-mannosylation of E-cadherin, cellular adherence, and embryonic gastrulation

2020 ◽  
Vol 31 (3) ◽  
pp. 167-183 ◽  
Author(s):  
Jill B. Graham ◽  
Johan C. Sunryd ◽  
Ketan Mathavan ◽  
Emma Weir ◽  
Ida Signe Bohse Larsen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Transmembrane Protein ◽  
Homophilic Binding ◽  
Polytopic Membrane Protein ◽  
E Cadherin

Here we characterize TMTC3 as an ER, polytopic membrane protein with C-terminal luminal-facing TPRs, and an O-mannosyltransferase of E-cadherin. O-mannosylation of cadherins by TMTC3 affects cellular adherence, E-cadherin homophilic binding, and embryonic gastrulation, helping to explain the basis of a number of TMTC3-associated disease variants.

Sign in / Sign up

Export Citation Format

Share Document